Prior to 1974, there were very few people wearing lap/shoulder belt restraints and measurement of restraint performance was not possible with existing field accident data. Accordingly, Wilson and Savage (1)* predicted the effectiveness of lap/ shoulder belts by analysis of 706 fatal accident cases on a case-bycase basis. When the inertial locking retractor and the starter interlock were introduced, lap/shoulder belt usage increased dramatically. With more people wearing lap/ shoulder belts and with the gathering of new accident data, it becomes possible to measure the effectiveness of lap/shoulder belts based on actual field observations.
This paper will discuss lap/shoulder belt studies made by the authors, the Highway Safety Research Institute, and the Highway Safety Research Center and compare their results. The paper will conclude with an assessment of lap/shoulder belt effectiveness, based on actual field data.